The present invention relates to a pneumatic tire having a good noise performance improved without deteriorating a drainage property.
Pneumatic tires are usually provided on its tread portion with one or a plurality of wide circumferential main grooves which extend in the circumferential direction of tire. However, such circumferential grooves are easy to generate columnar resonance during running, so the tires tend to be poor in noise performance. If the width of the circumferential grooves is decreased for the purpose of improving the noise performance, the drainage performance is deteriorated. Like this, the noise performance is repugnant with the drainage performance.
Various proposals to improve these performances have been made. For example, JP-A-2003-146024 discloses a pneumatic tire in which for the purpose of improving the wet grip performance without impairing the noise performance, at least one corner between the tread surface and the wall of a circumferential main groove is cut off to form a slant groove wall, and fine grooves having a width of 0.3 to 1.2 mm and a depth of 0.3 to 1.5 mm are provided in the slant groove surface at intervals of 1.4 to 3.0 mm.
It is an object of the present invention to provide a pneumatic tire having an improved noise performance without deteriorating the drainage performance.
A further object of the present invention is to provide a heavy duty pneumatic tire having excellent noise and drainage performances.
These and other objects of the present invention will become apparent from the description hereinafter.